Software Vault: The Diamond Collection/The Diamond Collection (Software Vault)(Digital Impact).ISO/cdr14/sprster.zip/SPHSASCI.TXT

Text File | 1995-01-20 | 118KB | 2,924 lines

SPORTSTER HIGH SPEED MODEMS
with V.42 bis
Reference Guide
1994 by U.S. Robotics, Inc.
8100 North McCormick Blvd.
Skokie, Illinois 60076-2999
All Rights Reserved
Revision Date:  9/9/94

TABLE OF CONTENTS

Sportster Configuration

Factory Configuration (&Fn and Yn)              5
Permanent Configuration Templates (&Fn)         5
Programmable Templates (Yn)                     6
Customizing Your Defaults (&Wn)                 6
Using AT Commands                               7
Resetting the Modem (Z)                         8

Placing Calls

Dial (D)                                        9
Cancel Dialing                                  9
Dial Command Options                            9
Dial Type_Pulse or Tone                         9
Adaptive Dialing (X2-X4)                       10
Wait for Another Dial Tone (W)                 10
Pause (,)                                      10
Slash (/)                                      10
Dial and Return to Command Mode (;)            10
Dialing Letters (")                            11
Transferring Calls (!)                         11
Wait for an Answer (@)                         11
Reversing Originate/Answer Frequencies(R)      11
Dialing Stored Numbers (DSn)                   12
Redialing                                      12
Dial the Last Dialed Number (DL)               12
Re-execute the Last Command (A/)               13
Answering                                      13
Suppressing Auto Answer                        13
Manual Answer                                  13
Points to Remember                             14
Disconnecting and Hanging Up                   14
Escape Code Operations (+++)                   14
Modem Response to +++                          14
Returning Online (On)                          14
Hanging Up (Hn)                                15
Break Handling (&Yn)                           15
International Calls                            15
ITU-T/Bell Answer Sequence (Bn)                15
Guard Tone (&Gn)                               15
Pulse Dial Make/Break Ratio (&Pn)              16
ITU-T V.21_300 bps                             16
ITU-T V.23_1200/75 bps                         16

Temporarily Changing a Setting

Tone Dialing                                   17
Speaker                                        17
Volume Control (Ln)                            17
Speaker Control (Mn)                           18
Local Echo                                     18
Command Mode Local Echo (En)                   18
Online Local Echo (Fn)                         18
S-Registers                                    18
Result Codes                                   19
Response Modes (Vn)                            19
Quiet Mode (Qn)                                19
Result Code Options (Xn)                       20
Additional Result Code Options (&An)           21
Error Control (&Mn)                            22
Auto Answer with Error Control                 22
Data Compression (&Kn)                         23
Data Rate Commands                             23
Software Requirements                          23
Serial Port Rate (&Bn)                         24
Connection Rate (&Nn)                          24
Flow Control                                   24
Warning on Software Flow Control               25
Software Flow Control Precautions              25
Transmit Data Flow Control (&Hn)               25
When it is Required                            25
Received Data Flow Control                     26
Hardware Control (&Rn)                         26
Software Control (&In)                         26
Serial Operations                              27
Carrier Detect (&Cn)                           27
Data Terminal Ready (&Dn)                      27
Data Set Ready (&Sn)                           28

Getting Help

Inquiries (In)                                 29
S-Register Query (Sr?)                         31
Stored Phone Number Query (&Zn?)               31
Last-Dialed Number Query (DL?)                 31
Help Screens                                   31
Stop/Restart Display                           31
Cancel Display                                 31
Basic Command Set ($)                          31
Ampersand Command Set (&$)                     31
Dialing (D$)                                   31
S-Register Functions (S$)                      31

Testing the Modem

Testing with &T                                32
Dial Test_S16=2                                35

Other Operations

Fax Operations                                 36
Voice/Data Communications                      37

Technical Specifications

Compatibility                                  38
The Serial Interface                           38
Default Settings                               40

Modem Concepts

How Modems Work                                43
Modem Configuration                            43
Line Travel                                    43
Digital Data                                   43
Flow Control                                   44
Error Control                                  44
ITU-T V.42 Handshaking                         44
MNP Handshaking                                45
Data Compression                               45
Flow Control                                   45
Online Fallback/Fall Forward                   46
Throughput Guidelines                          46
Achievable Throughput Statistics               47

            SPORTSTER CONFIGURATION

The Sportster is preconfigured at the factory so you should be able to
connect the modem, set up your communications software, and be ready to
send and receive data.  Many users won't need to change the default
configurations, but if you want to, this guide will tell you how.  Many of
the functions described below can be handled by your communications software,
but you also have the power to place your computer in Terminal mode
(via your communications software) and control the modem directly.

NOTE:  Unless otherwise indicated, settings listed as "default" are based
on those set for the modem when it is shipped.

FACTORY CONFIGURATION (&Fn and Yn)
The Sportster is preconfigured at the factory with three permanent and
two programmable templates.


Permanent Configuration Templates (&Fn)

The following permanent templates come with your Sportster.  The default
template consists of the most reliable settings, but these settings may
not work for all users.

&F0     This template does not include performance features, such as a
    fixed serial port rate or hardware flow control.  What it does
    offer is compatibility with nontypical computers or software that
    cannot handle flow control and other features.

&F1     Default.  This template sets the modem to hardware flow control,
    a fixed serial port rate, the highest level result codes, and
    the most complete result-code set. The &F1 Hardware Flow Control
    template is recommended for all IBM-compatible computers, as long
    as your communications software supports hardware flow control, a
    fixed serial port rate, and the advanced result-code subset.

    NOTE:  We also recommend that users of Macintosh computers invest
    in a Hardware Handshaking cable (instead of the standard cable),
    use this template, and use software that supports hardware flow
    control. (Sportster Mac&Fax modems come with this hardware
    handshaking cable)

&F2     This is a software flow control template.  We recommend you
    do not use software flow control, and thus, this template.
    However, if you use a Macintosh, see the note above.  In
    addition, some computers are limited to three-wire cables that
    do not support hardware flow control signals.  If this is the
    case, review the warning on software flow control later in this
    guide.

To load the &F2Software Flow Control template and save it as your
power-on/reset default, enter the following command:

          AT&F2&W <Enter>

NOTE:  Refer to the Programmable Templates section for more information
on selecting and modifying templates to save as your start-up configuration.

If you need a low performance template because of data-transfer difficulties,
flip DIP switch 7 ON and reset the modem (ATZ command), or load the &F0
Low Performance template by entering the following command:

          AT&F <Enter>

NOTE:  When the modem receives the above command, it assumes you want to
load the &F0 template because there is no position number.  It is the same
to enter AT&F as to enter AT&F0.

This template allows you to communicate with nontypical systems that
cannot handle flow control and other features.


Programmable Templates (Yn)

In addition to the &Fn permanent configuration templates, two programmable
templates are provided.  Your programmable templates are located in
nonvolatile random access memory (NVRAM).

The Sportster is shipped to load NVRAM template 0 (or Y0) for its
power-on/reset default settings.

Possible NVRAM templates:

Y0      Loads the NVRAM template 0 (stored with template &F1
    Hardware Flow Control settings).  Default.
Y1      Loads the NVRAM template 1 (stored with template &F2
    Software Flow Control settings).

If you want to switch the power-on/reset default NVRAM template from
Y0 to Y1, enter the Yn command, then reset the modem with the Z command.

        AT Y1 Z <Enter>

To customize other defaults you want to store in NVRAM as part of your
customized power-on/reset template, use the &Wn command (below).

WARNING:  The Yn command, which selects template settings to use as
the power-on/reset default, may select different power-on/reset
default settings than those currently loaded (if you altered the settings
during the current session).  Before changing a template, you may want to
use option 4 of the Inquiry (I) command to display the current settings.

        AT I4 <Enter>

The Y setting on the ATI4 screen indicates if Y0 or Y1 is the
power-on/reset default.  If you want to check all the NVRAM settings
in both the Y0 and Y1 templates, use option 5 of the Inquiry command (I).

        AT I5 <Enter>


CUSTOMIZING YOUR DEFAULTS (&Wn)

When the modem is shipped, it reads template 0 in NVRAM as the
power-on/reset default.  Template 0 (Y0) is initially loaded with &F1
permanent configuration settings.  Although you cannot alter the &F1
template, you can add, delete, or modify the settings stored in your
NVRAM templates.  It is more likely, however, that you will want to
keep your power-on/reset default settings and simply change a setting for a
current session.  Refer to Temporarily Changing a Setting in this guide
for more information.

If  you want to modify your default configuration settings, use the
&Wn command.  Possible settings are:

&W0     Modifies the NVRAM 0 template (Y0).

&W1     Modifies the NVRAM 1 template (Y1).

Typically, users prefer the default settings stored in NVRAM when the
modem is shipped, but you may set up different power-on/reset defaults.
For instance, if your system supports hardware flow control, you can
set your Y1 template to the settings for hardware flow control so both
templates set the modem for hardware flow control.
(The Y0 template is shipped with hardware flow control settings.)

            AT &F1 &W1 <Enter>

NOTE:  Yn is unique because it writes itself to NVRAM_you do not need to
use the &Wn command to load a programmable template.

Similarly, if your system only supports software flow control, you can
set your Y0 template to the settings for software flow control so both
templates set the modem for software flow control.
(The Y1 template is shipped with software flow control settings.)

            AT &F2 &W <Enter>

You may also specify the entire configuration in a single command string
that ends with the &Wn command.  The following example sets the modem for
the current session and stores the configuration in NVRAM 1 (or Y1).

            AT &K3 &W1 <Enter>

After sending a configuration to NVRAM, you can change any setting just
for the current session, as in the following example.  The NVRAM
configuration remains intact.

            AT &K3 <Enter>

But if you want the new setting to be a default, write it to NVRAM at the
same time, as in the following example, which saves the setting to NVRAM
template 0.

            AT &K3 &W <Enter>

If you've sent the modem commands to change settings throughout your
session and want to save your current configuration, send just the &Wn
command.  The current settings are then written to NVRAM 0 (or Y0) in
the example below.

            AT&W <Enter>

If you cannot use hardware flow control and need to use Xmodem-type
file transfer protocols, use either Y0 or Y1 for a no flow control
configuration with no error control.

            AT &F &M &W <Enter>
                   or
            AT &F &M &W1 <Enter>


USING AT COMMANDS

To send commands directly to your modem, first put your computer in
Terminal mode.  Some communications programs do this automatically upon
loading.  Others require you to display a communications terminal screen,
press a Function key, or perform some other operation.  If necessary,
refer to your communications software documentation for instructions.

1.      Type all commands in either upper case (AT) or lower case (at),
    but not a combination (At).

2.      All commands except A/ (re-execute last command) and +++
    (escape code) are preceded by the AT prefix and are executed
    with the Enter/Carriage Return key (<Enter>).

3.      Command string length = 40 characters, maximum.  The modem doesn't
    count the AT prefix, Carriage Return character, or spaces.  In a
    dial string, it counts but doesn't act on punctuation such as
    hyphens and parentheses.

4.      A missing numeric parameter is assumed to be zero, as in the
    command to hang up;  ATH <Enter> is the same as ATH0 <Enter>.


RESETTING THE MODEM (Z)

If you've changed several current settings and want to reset to your
modem, use the following command.

ATZn <Enter>

Z0      Resets modem to NVRAM profile selected by Y command
Z1      Resets modem to NVRAM profile 0
Z2      Resets modem to NVRAM profile 1
Z3      Resets modem to factory default profile 0 (&F0)
Z4      Resets modem to factory default profile 1 (&F1)
Z5      Resets modem to factory default profile 2 (&F2)

The modem reads its DIP switch settings and resets to its NVRAM defaults
(DIP switch 7 OFF) or the &F0 Low Performance template (DIP switch 7 ON)
settings.

Use the ATZ command if you've changed the position of DIP switches 1-7
while the modem is on, so that the modem can read the new settings.  The
only other way to initiate a new setting for switches 1-7 is to turn the
modem off and on again.

NOTE:  You cannot issue additional commands on the same line with the
Z command for the modem will ignore everything following the Z parameter.
For example:  ATZE1Q0 would be an invalid command.  The modem will ignore
the E1Q0 portion of the command string.


            PLACING CALLS

NOTE:  Unless otherwise indicated, settings listed as "default" are
based on the hardware flow control template stored in NVRAM when the
modem is shipped.


DIAL (D)

To dial a phone number and place a call without using your software's
dialing directory, first put the computer in Terminal mode.  Then type
the AT and D commands, the number you wish to connect with, and press Enter.
Spaces in our command examples are ignored by the modem and are only
included for readability.

            ATD 1234567 <Enter>

Unless you lowered your modem's speaker volume, you will hear the modem
go off hook and dial the telephone number, followed by a series of
handshaking signals.

The Dial command string may include up to 40 characters.  The modem
counts but ignores punctuation characters such as parentheses and hyphens.
It does not count spaces, the AT prefix, or the Carriage Return key
(<Enter>) required to execute the command.

The modem also executes any other commands or options included in the
command line.  The following Dial command example instructs the modem
to turn off the speaker (M0), and dial (D) the phone number
(1234567) using tone dialing (T).

            AT M0 DT 1234567 <Enter>

You may want to review the many options on the next several pages
that are available for tailoring Dial strings.  The most typically
used are the Dial Type_Pulse or Tone, and the Pause options_comma,
slash, and W.


Cancel Dialing

To cancel Dial command execution, press <any key>.  If you inadvertently
hit a key on the keyboard while the modem is dialing, the call is
canceled.  If this occurs, type the A/ command, which re-executes the last
command you entered.


Dial Command Options

You can modify the dial string according to the needs of the connection.
Listed below are options available to you when entering the Dial string.

Dial Type_Pulse or Tone

    The modem defaults to pulse (rotary) dialing.  To have the modem
    use tone dialing, which includes the asterisk (*) and pound
    sign (#), use the T command.

    Dial type commands may be included in the Dial string (ATDT number)
    or, issued separately (ATT or ATP).  However, if you'll always use
    tone dialing, write tone dialing to NVRAM as the modem's default
    and/or use adaptive dialing, described below.

    NOTE:  You can switch from one dial type to another within a dialing
    sequence.  The modem remains set to the last dialing type instruction
    until it is reset (ATZ command), or it receives a different dial-type
    command.


Adaptive Dialing (X2 through X4)

    When any of the X2 through X4 (default) result code options is
    in effect and you do not issue a dial type in the Dial string,
    the Sportster defaults to pulse dialing.  If you issue a tone
    dial command,  the Sportster will default to Hunt dialing,
    beginning with tone and adapting to pulse when necessary.  For
    instance, if the phone company's central office does not have
    tone-detection equipment, the modem automatically reverts
    to pulse dialing.


Wait for Another Dial Tone (W)

    This command is useful in situations where you must wait for a
    second dial tone before continuing to dial.  For example, if
    you need to dial for an outside line, as in the following example,
    the Sportster continues to dial as soon as it detects the next dial
    tone.
            ATD9W1234567 <Enter>

    NOTE:  This command executes only if result code option X3 or X4
    (default) has been issued.  If the modem is set to X2 or lower,
    the modem interprets the W as a comma (two-second pause).


Pause (,)

    A comma causes a two-second delay in the dial sequence.  The
    following example contains four-second delays at several points.

            ATDP 9,,7654321,,55555,,1 312 1234567 <Enter>

    The first four-second pause is to access an outside line after
    dialing 9, but you may wish to use the W option, just described.
    The second pause is to make sure the remote system is ready for
    the user's account number, and the third, to delay before dialing
    the long-distance number. Such pauses, however, may not be necessary.
    Experiment and use delays only as required.  The duration of the
    delay can be changed by using the S8 register.  The default duration
    of the delay is 2 seconds.


Slash (/)

    A slash (/) can be used in any command string to make the modem
    pause for only 125 milliseconds.  Some users find it helpful to
    have the shorter delay of a series of slashes, rather than the
    2-second comma pause.


Dial and Return to Command Mode (;)

    If your phone is plugged into the modem, you can use this option
    to have the modem Auto Dial a telephone rather than a modem.
    The Sportster dials, remains off hook, and returns the OK message,
    indicating it is in Command mode.

    For example, to have the modem place a voice call, enter the Dial
    command with a semicolon.

                ATDT5551234; <Enter>

    When the modem returns the OK result, pick up your phone receiver
    so you can talk to the other party, and send the command that
    hangs up the modem.
                ATH <Enter>

    Similarly, if you can call a recorded weather or other service,
    have the modem Dial, listen to the recording over the modem's
    speaker and, when you are finished, instruct the modem to hang up.


Dialing Letters (")

    Quotation marks are used to make the modem dial abbreviations and
    acronyms used as phone numbers, such as DIAL USR (the U.S.
    Robotics Sales Department's 800 number).  This option is called
    Quote mode.  Quotation marks are inserted at the beginning of
    the alphabetic string.
                ATDT "DIAL USR <Enter>

    NOTE:  If you are including another command after the dial
    string, use closing quotation marks before the additional command.

                ATDT "DIAL USR",,,1234<Enter>


Transferring Calls (!)

    This command is used for modems installed where other modems share
    the phone line.  The modem flashes the switch-hook.  That is, it
    goes off hook 0.5 seconds, on hook for 0.5 seconds, and off hook
    again to dial the specified extension.  The following example
    includes instructions to return to Command mode (;) and to
    hang up (H).

                ATDT !1234;H <Enter>


Wait for an Answer (@)

    Some online services answer the phone and return a tape-recorded
    request for information before processing transactions.  In such
    instances, the @ command can be used in the Dial string to tell the
    modem to detect at least one ring, wait for five seconds of silence
    at the other end of the call, and then continue to execute the
    Dial string.

    To use the @ command, set the modem result code option to X3 or
    X4 (default).  If the modem is set to X2 or lower, the modem
    returns an ERROR message when encountering the @ character in a
    command string.

    In the next example, the modem is set to the X3 result code option
    and dials a banking service.  Each occurrence of @ in the example
    indicates a five-second wait for silence.  That is, for taped
    requests from the bank for a password (12345), an account number
    (6789), and a transaction code (2).  The transaction code might
    indicate, for example, a request for an account balance.

            ATX3 DT5551234 @ 12345 @ 6789 @ 2 <Enter>

    If the necessary conditions do not occur_no rings, or no following
    five seconds of silence_the modem times out as it normally would
    (after 60 seconds).  It then sends the message NO ANSWER to the
    screen and aborts the call.


Reversing Originate/Answer Frequencies (R)

    This command allows calls to an originate-only modem (a modem set
    up to send only).  It reverses the modem's originate/answer
    frequencies, forcing the Sportster to dial out at the answer
    frequency.  The command follows the Dial command, before or
    after the phone number.

            AT D1234567R <Enter>
            AT DR1234567 <Enter>


Dialing Stored Numbers (DSn)

    You can store up to four frequently used telephone numbers
    in nonvolatile random-access memory (NVRAM).  Use the &Zn=s
    command to store telephone numbers, where n is the position
    of the number in NVRAM (03) and s is the stored number.  The
    following command string stores the telephone number (4441212)
    at position 1 in NVRAM.
                AT&Z1=4441212 <Enter>

    To dial a stored number, use the DSn command, where n is the
    position of the number in NVRAM (03).  In the first example,
    the modem dials the phone number stored at position 0.  In the
    second, the modem dials the phone number stored at position 3.

            ATDS0 <Enter>
            ATDS3 <Enter>
    You can also store a partial dial sequence.  If you often call
    a set of phone numbers and only their last three or four digits
    differ, it might be useful to store the other digits.  The
    following example stores a partial phone number at position 1.

            AT&Z1 = 9W1 616 123 <Enter>

    Once you have stored the partial phone number in NVRAM, use the
    DSn command to dial the partial number, placing a slash (/),
    then the remainder of the number after the DSn command.  The
    slash separates the DSn number from the remainder of the string,
    yet maintains the Dial command.  You can also use a comma (,)
    to insert a 2-second delay that separates the number.

            AT DS1/4567 <Enter>

    NOTE:  Do not include modem settings in the &Zn=s string.  If
    the call requires special settings, insert them in the command
    string before the DSn command.  For example, &K3 (selective data
    compression) is inserted before the Dial command to call the number
    stored at position 0.

            AT&K3 DS0 <Enter>

    This establishes &K3 as the current setting.  To return to default
    data compression mode after the call, issue the following command.

            AT&K1 <Enter>


REDIALING

The most frequent reason for redialing is receipt of a busy signal.  The
Sportster modem provides two redialing options, as follows.

Dial the Last-Dialed Number (DL)
    When you want to redial a number, enter the DL command.  The
    modem dials the last-dialed number, which it has stored in a
    special buffer.
            ATDL <Enter>
    To display the number stored in the last-dialed buffer, use
    the following query.
            ATDL? <Enter>

    To write the last number dialed to NVRAM, use &Zn=L where n
    is the position in NVRAM.  The following example stores the
    last-dialed number at position 3.

            &Z3=L <Enter>

    If a number is already stored at position 3, that number is
    overwritten with the last-dialed number.


Re-execute the Last Command (A/)

    Another option for redialing is to enter the A/ command.  This
    command does not require the AT prefix or a Carriage Return.

            A/

    When the modem receives a command, it stores it in its command
    buffer until it receives the next AT command.  Note that if
    you've sent the modem an additional command since the Dial command,
    A/ repeats that command instead of redialing.


ANSWERING

Your Sportster modem is shipped with DIP switch 5 ON, Auto Answer suppressed.
To set the modem to automatically answer incoming calls, do one of the
following.

    Before powering on the modem...

    Set DIP switch 5 OFF.  When you power on, the modem answers
    incoming calls on the first ring.If you want the modem to
    answer after several rings, set DIP switch 7 OFF.  Specify
    the ring you want the modem to answer on in NVRAM (default=1 ring).
    The valid range is 1-255 rings.  Power off the modem and power it
    on again with its new DIP switch and NVRAM settings.

    During a current session...

    Issue the following command to have the modem answer on the fourth
    ring:           ATS0=4 <Enter>

    When the modem senses a call, it sends the RING result code to
    your screen, goes off hook, and sends the remote modem a
    high-pitched answer tone.  If there is no Carrier Detect within
    60 seconds, the modem hangs up.  If the connection is made, the
    modem returns a CONNECT result code.  When the call is disconnected
    by you or the remote user, the modem hangs up and returns the
    NO CARRIER code.


Suppressing Auto Answer

To disable Auto Answer, set DIP switch 5 ON before powering on the modem,
or set the modem to answer on zero (or no) rings during the current session.

            ATS0=0 <Enter>

NOTE:  The S-Register setting S0=0 cannot be saved to NVRAM.


Manual Answer

If you've disabled Auto Answer but are expecting an incoming data call,
use the Manual Answer command.  Send the modem the following command
after the RING result code appears on your screen.

            ATA <Enter>

When the call is disconnected, the modem returns to its original state,
Auto Answer disabled.

Points to Remember

1.      You can set the modem to receive calls when you're not at your
    computer.  Load your communications software as you normally do,
    and set the modem to Auto Answer.  Also set your software's
    file-save function to save incoming messages and/or files.

2.      If you've attached your phone so it can be used for conventional
    calls, disable Auto Answer when you are not expecting incoming
    data calls.  Otherwise, your modem may answer the phone before
    you do, greeting a voice caller with a high-pitched, irritating
    answer tone.


DISCONNECTING AND HANGING UP

The commands outlined below describe how you can instruct the modem to
disconnect the call and hang up the line.


Escape Code Operations (+++)

Once the modem is online to another system, the only command it recognizes
is an escape code of three plus symbols that forces the modem into
Online-Command mode.  Issue the escape command in the following sequence.

∙       Wait one second after sending the last item of data.
∙       Type three plus symbols (+++).
∙       Wait one second before typing any data.

Do not type the AT prefix or a Carriage Return.  The guard time of one
second before and after prevents the modem from misinterpreting the
presence of the +++ symbols in the transmitted data stream.

If necessary, the character used in the escape code or the duration of
the guard time can be changed by resetting Register S2 or S12.  See the
Quick Installation Guide for more information.

Modem Response to +++

When the modem receives +++, by default it enters Online-Command mode
and returns the OK result code.  It maintains the connection and is ready
to act on commands.  You may then choose one of the following options.

∙       Issue commands to the modem and then return it online.
∙       Hang up the modem.

Alternatively, if you want the modem automatically to hang up on receiving
the +++ escape code, set Register S14 to 1 and write the command to your
NVRAM templates:

        ATS14=1 &W &W1 <Enter>

The modem disconnects and sends the NO CARRIER result code to the screen.


Returning Online (On)

After forcing the modem into Online-Command mode with the escape code
sequence, you can issue commands and then toggle the modem back online
with the O command, as in the following example.

                AT Q1 O <Enter>

    O0      Return online (normal).
    O1      Return online and retrain.  If errors occur during a non-ARQ
        connection, try this option.  The modem returns online and
        requests that both modems resynchronize.


Hanging Up (Hn)

At its default setting, the escape code forces the modem into Online-Command
mode but leaves the line open.  To hang up the modem, issue the following
command once the modem sends the OK result code.

            ATH <Enter>

    H0      Hang up (go on hook).
    H1      Go off hook.


Break Handling (&Yn)

This command lets you send a Break to abort data transfer without
disconnecting from the phone line interface.

    &Y0     Destructive, no Break transmitted:  the modem clears the
    data from its transmit buffer (all data is lost) but does not
    transmit the Break to the remote modem.

    &Y1     Destructive, expedited:  the modem clears the buffer and
        immediately sends a Break to the remote modem. Default.

    &Y2     Nondestructive, expedited:  the modem retains data in the
        transmit buffer, but immediately sends a Break to the
        remote modem.

    &Y3     Nondestructive, unexpedited (send Break in sequence):  the
        modem transmits any buffer data received before the Break,
        sends the Break, and then sends any subsequent input from
        the computer.

NOTE:  If the call is under MNP5 data compression, destructive Breaks cause
both modems to reset their data compression tables.  When transmission
resumes, the modems build new tables, and the result is lower
than normal throughput.


INTERNATIONAL CALLS

The following commands apply to international calls.

ITU-T/Bell Answer Sequence (Bn)

To answer international calls, use the default B0 setting.

    B0      Default.  This setting is required for V.32  or higher
        modems to answer V.32 or higher calls.  It also selects
        the ITU-T V.25 answer sequence, used outside of North America.

    B1      This setting selects the Bell 2225 Hz answer tone used
        in the U.S. and Canada and may be used when the remote
        modem operates at only 2400 bps or lower.  However, if
        the modem is set to B1, it won't be recognized by V.32
        bis modems and can't answer calls at 9600 bps and above.


Guard Tone (&Gn)

The United Kingdom and some Commonwealth countries use phone switching
systems that require answering modems to send an 1800 Hz guard tone after
they send an answer tone.  Some other European phone networks require a
550 Hz guard tone.  Guard tones are not used in the United States or Canada.

    &G0     No guard tone, U.S./Canada.  Default.

    &G1     550 Hz guard tone follows answer tone.  Requires B0 setting.

    &G2     1800 Hz guard tone follows answer tone, United Kingdom and
        some Commonwealth countries.  Requires B0 setting.


Pulse Dial Make/Break Ratio (&Pn)

This command sets the ratio of the off-hook/on-hook (make/break) interval
for pulse dialing.  The default sets the modem for use in North America.
The ratio must be changed if the modem is used to dial out in the
United Kingdom and some Commonwealth countries.

    &P0     Make/break ratio, U.S./Canada:  39%/61%.  Default.

    &P1     Make/break ratio, United Kingdom, some Commonwealth
        countries:  33%/67%.


ITU-T V.21_300 bps

Select this option to call or answer overseas modems at 300 bps.  In
V.21 mode, the modem answers Bell 103/V.21 calls, but only originates
V.21 calls.  This option is enabled in Register S27 with the following
command.
            ATS27=1 <Enter>


ITU-T V.23_1200/75 bps

Some United Kingdom and European systems require a 1200-bps speed with a
75-bps back channel.  This option is enabled with Register S34=8. It is
also recommended that you force 1200 connections with &N2 and disable
error correction with &M0 to establish a V.23 connection with the
following command.
            AT &M0 &N2 S34=8 <Enter>


            TEMPORARILY CHANGING A SETTING

When you change a setting, the modem retains it until you do one of the
following.

∙       Change the setting again.
∙       Issue the ATZ command to reset the modem.
∙       Turn the modem off and power it on again.

The parameters described in this section are organized in the order of
their likely use.  That is, those you are most likely to use appear at
the beginning of the section, and those you are least likely to use
appear toward the end.


TONE DIALING

The modem defaults to pulse (rotary) dialing.  To have the modem use
tone dialing, which includes the asterisk (*) and pound sign (#), use
the T command.
            ATDT 4445555 <Enter>

To have the modem always use tone dialing, use the T and &W commands:

            AT T &W &W1 <Enter>


SPEAKER

The modem's speaker enables you to monitor the dial-connect process.  There
are several ways to make use of this feature.  After the Sportster modem
dials a number, it waits up to 60 seconds for a high-pitched answer tone
from the other modem, immediately followed by data signals, called a carrier.  These signals
must occur before a data link is established.

At the default X4 setting, the modem sends your screen the NO CARRIER
message after 60 seconds.  If you listen to the speaker and realize you
have received a voice answer, you can respond immediately, instead of
waiting for the modem to time out, by pressing any key on the keyboard.
This cancels the call.

You can also hear if dialing is proceeding too quickly for the system.
Terminate the call (press any key) and retype the Dial command, but
insert a comma (,) or a couple of slashes (/), to have the modem pause
during the dialing process.


Volume Control (Ln)

The following options allow you to adjust the speaker volume if you have
an internal modem.  You can adjust an external modem's volume via its
volume switch.

    L0      Low.
    L1      Low.
    L2      Medium.  Default.
    L3      High.


Speaker Control (Mn)

This command disables the speaker entirely or sets the speaker to
monitor different segments of the dial-connect sequence.

    M0      Disables the speaker entirely so that you don't hear
        the modem go off hook, dial, etc.

    M1      The speaker is on until Carrier Detect.  Default.  You can
        monitor call progress until the Sportster detects the
        remote modem's carrier signals, or until the 60-second
        timeout and result code display.  At Carrier Detect,
        the modem disconnects the speaker and data-transmission
        sounds are suppressed.

    M2      The speaker is on continuously, including during data
        transmission.

    M3      The speaker doesn't go on until after the last digit
        is dialed, then goes off at Carrier Detect.


LOCAL ECHO

Local echo is the display of what you type at the keyboard and online
echo display of data the Sportster transmits to another modem.  The En
command controls the display of your typed commands, when the Sportster
is in Command mode.  The Fn command controls the display of data when
your modem is online to another system.


Command Mode Local Echo (En)

The power-on/reset default for command mode local echo is set with
DIP switch 4.  The Sportster modem is shipped with DIP switch 4 OFF,
enabling local echo of your typed commands.   Use the En command to
control the local echo for a current session, independent of the switch
setting.  This command may not be stored in NVRAM.

    E0      Command mode echo OFF.  The modem does not display
        keyboard commands.

    E1      Command mode echo ON.

NOTE:  If double characters appear on the screen, both the modem's and
software's local echoes are on.


Online Local Echo (Fn)

This command causes the modem to display a copy of the data it is
transmitting to another system.  Many systems, however, return a copy of
received data, which is called a remote echo.  If the modem's online echo
is ON and there is also remote echoing, double characters appear on the
screen.

In some microcomputer documentation, the term duplex is applied to online
local echoing, although the term is not technically accurate.

    F0      Online echo ON.  Sometimes called half duplex.  As the
        modem transmits data to a remote system, it also sends
        a copy of the data to the screen.

    F1      Online echo OFF.  Sometimes called full duplex.  Default.


S-REGISTERS

The S-Registers are used to set various timing parameters and to redefine
selected ASCII characters and other configuration options.  Refer to the
Quick Installation Guide for a summary of S-Register functions and setting
options.

Users typically require the default values.  To change a setting, use the
ATSr=n command, where r is the register and n is a decimal value from
0-255 (unless otherwise indicated).

The example below sets the modem's test timer (S-Register 18) to 10 seconds.

            ATS18=10 <Enter>

The modem does not perform a value-range check.  Some values you select
may not work with some equipment, and you'll have to readjust the settings.

Use ATSr? to display the contents of a register, as follows.

            ATS18? <Enter>


RESULT CODES

Four commands control the result codes that the modem returns to the screen.

    Vn      Numeric/verbal response mode
    Qn      Display/suppress all result codes
    Xn      Result code options
    &An     Display/suppress additional result code options


Response Modes (Vn)

Result codes are sent to the screen in words (Verbal mode) or numbers
(Numeric mode).   The power-on/reset default for response modes is set
with DIP switch 2.  The Sportster modem is shipped with DIP switch 2 OFF,
enabling Verbal mode.

Use the Vn command to select verbal or numeric result codes for a current
session, independent of the DIP switch setting.  This command may NOT be
stored in NVRAM.

    V0      Numeric mode.  Numeric result codes are followed by a
        Carriage Return but no Line Feed, as in the following
        example, where a 3 is returned (for NO CARRIER).

            ATD1234567 <Enter>
            becomes
            3TD1234567 <Enter>

    V1      Verbal mode.  Verbal responses are preceded and followed
        by a Carriage Return and a Line Feed, as shown below.

            ATD1234567 <Enter>
            NO CARRIER


Quiet Mode (Qn)

Enable/suppress the display of result codes.

The power-on/reset default for response modes is set with DIP switch 3.  The
Sportster modem is shipped with DIP switch 3 ON, to display result codes.

Use the Qn command to control the display for a current session, independent
of the DIP switch setting. NOTE: This command may not be stored in NVRAM.

    Q0      Result codes are displayed.
    Q1      Result codes are suppressed (made quiet).
    Q2      Result codes are suppressed only in Answer mode.


Result Code Options (Xn)

    You have five options, X0 through X4, for selecting the result-code
    set best suited to your applications, as shown in the tables below.

    X0      Basic set, returns the first five codes (0-4) in the
        following table.

    X1      Extended set, codes 0-5, 10, 13 and 18, that adds
        rate-specific CONNECT messages to the Basic set.  This set
        also includes all &An result codes.

    X2-4    The default is X4.  These options include the X1 set,
        call-progress codes 6 or 7, and 8, and the functions listed
        in the following table.

NOTE:  By default, the modem is also set to &A3, which selects additional
results that report the protocols used in the connection.


            Result Code Options

                Setting
Result Codes    X0      X1      X2      X3      X4
0/OK             *      *       *       *       *
1/CONNECT        *      *       *       *       *
2/RING           *      *       *       *       *
3/NO CARRIER     *      *       *       *       *
4/ERROR          *      *       *       *       *
5/CONNECT 1200          *       *       *       *
6/NO DIAL TONE                  *               *
7/BUSY                                  *       *
8/NO ANSWER                             *       *
10/CONNECT 2400$        *       *       *       *
13/CONNECT 9600$        *       *       *       *
18/CONNECT 4800$        *       *       *       *
20/CONNECT 7200$        *       *       *       *
21/CONNECT 12000$       *       *       *       *
25/CONNECT 14400$+      *       *       *       *
43/CONNECT 16800$+      *       *       *       *
85/CONNECT 19200$+      *       *       *       *
91/CONNECT 21600$+      *       *       *       *
99/CONNECT 24000$+      *       *       *       *
103/CONNECT 26400$+     *       *       *       *
107/CONNECT 28800$+     *       *       *       *

Functions

Adaptive Dialing                *       *      *
Wait for 2nd Dial Tone (W)              *      *
Wait for Answer (@)                     *      *
Fast Dial                       *              *

+ V.FC modems
$ V.34 modems

NOTE:  More CONNECT messages indicate an error control connection, the
call modulation, or the error control and data compression used.  See
Additional Result Code Options (&An), after this section.


            Result Code Definitions

Result Code             Meaning

0/OK                    Command has been executed.
1/CONNECT               Connection established with another modem; if set
            to X0, connection may be 30028.8K bps; if X1 or
            higher, connection is at 300 bps.
2/RING                  Incoming ring detected.
3/NO CARRIER            Carrier detect has failed or carrier has been
            dropped due to disconnect.
4/ERROR                 Command is invalid.
5/CONNECT 1200          Connection established with another modem at 1200 bps.
6/NO DIAL TONE          Dial tone not detected during the normal 2 seconds,
            set in Register S6.
7/BUSY                  Busy signal detect; modem hangs up.
8/NO ANSWER             After waiting 5 seconds for an answer, modem hangs
            up; returned instead of NO CARRIER when the @ option
            is used.
10/CONNECT 2400         Connection at reported rate.  Same for results of
            4800 (18), 9600 (13), 7200 (20), 12K (21), 14.4K
            (25), 16.8K (43), 19.2K (85), 21.6K (91), 24K (99),
            26.4K (103), 28.8K (107).  NOTE:  Connections over
            9600 bps apply to V.32 bis and V.FC modems only.
            Connections over 14.4K bps apply to V.FC modems only.

Adaptive Dialing (HUNT) The modem attempts to use tone dialing and, if that
            doesn't work, reverts to rotary (pulse) dialing.
Wait for Another        The modem continues dialing as soon as it detects
    Dial Tone (W)       another dial tone.

Wait for an             The modem continues dialing when it detects 5
    Answer (@)          seconds of silence on the line.

Fast Dial               The modem dials immediately on dial-tone detect,
            instead of waiting the normal 2 seconds set in
            Register S6.


Additional Result Code Options (&An)

Use this command to enable/disable one of the following sets of error
control, modulation, or protocol result codes.

If you encounter software problems, it may be because your software expects
to find different result codes from those the modem is sending.  (The modem
defaults to &A3.)  Review your software documentation or try &A2, &A1,
or &A0.  You may need to call your software's technical support to find out
which &An setting they support.

&A0     ARQ (error control) codes are disabled.  This setting does not
    affect an error control connection; the modem returns standard
    CONNECT messages if result codes are enabled.

&A1     ARQ codes are enabled.  CONNECT/ARQ is displayed if the modem
    is set to X0 and the connection is 1200 bps and above.  The
    remaining results indicate connection rate and require X1 or above.
    If your software cannot handle the ARQ codes, select &A0.

&A2     V.32 modulation codes are enabled.  These results require a setting
    of X1 or higher.  If your software cannot handle the added modulation
    information, select &A1 or &A0.

&A3     Protocol codes are enabled.  Default.  Error control protocols
    reported are LAPM or MNP.  When the call is not under one of
    those protocols (and ARQ is not included in the result code), the
    modem reports NONE, for no protocol.

    If the modems are using data compression, the type of compression
    --V42BIS or MNP5--is added to the result code.  If your software
    cannot handle the added protocol information, select &A2, &A1,
    or &A0.

    Although these codes will return numeric identifiers if DIP
    switch 2 is ON or you've set the modem to V0, they are the
    same numeric identifiers used for &A2 result codes.  If you
    want &A3 protocol indicators, use Verbal mode (V1), and not
    Numeric mode (V0).


ERROR CONTROL (&Mn)

By default, the Sportster first attempts a connection using V.42 (LAPM)
error control and, if that doesn't succeed, it attempts an MNP connection.
If that doesn't succeed, the modem tries to connect without error control.

Error control is possible at rates of 1200 bps and above.  The following
options are available.

NOTE:  ARQ is U.S. Robotics' term for error control protocols that feature
error detection and automatic retransmission of corrupted blocks of data.

&M0     Normal mode, no error control.  Because of the nature of phone-line
    channels, this is never recommended for calls above 2400 bps unless
    you're using an error-correcting file-transfer protocol.

&M1     Reserved.

&M2     Reserved.

&M3     Reserved.

&M4     Normal/ARQ mode.  Default.  If the remote modem doesn't recognize
    the Sportster's error control signals_V.42 or MNP_the modem operates
    in Normal mode, as though it were set to &M0.

&M5     ARQ mode.  If the remote modem doesn't recognize the error control
    request_V.42 or MNP_the Sportster hangs up.

Always set the Sportster for error control, &M4 (default) or &M5, for calls
at speeds over 2400 bps.  Most users communicating with V.42- or
MNP-compatible modems will want error control at 2400 and 1200 bps, as well.

If you're dialing out and have trouble connecting, it may be because the
remote modem doesn't have MNP capability, and it misinterprets your modem's
MNP error control request.  If you know the remote modem doesn't support
MNP, disable MNP handshaking by setting Register S27 to 16 (ATS27=16).
The Sportster still connects, but without MNP error control.

To reset the modem for normal operations after the call, issue the ATZ
(reset) command, or set Register S27 to zero.


Auto Answer with Error Control

When set to &M4 or &M5 and a call comes in, the modem goes off hook and
responds to received error control signals.  If the Sportster doesn't
receive those signals and is set to Normal/ARQ mode (&M4), it answers
the call in Normal mode (&M0).  If it doesn't receive the signals and is
set to ARQ mode (&M5), it hangs up.


DATA COMPRESSION (&Kn)

When data compression is enabled, the transmitting modem detects redundant
units of data and recodes them into shorter units of fewer bits.  The
receiving modem decompresses the redundant data units before passing them
to the receiving computer.

Compression does not occur unless the modems can establish an error
control connection.

If the Sportster makes a V.42 connection, it negotiates V.42 bis compression.
If V.42 bis is not feasible, the connection remains under error control,
but without data compression.

If the Sportster makes an MNP connection, it negotiates for MNP Level 5
(MNP5) data compression.  If the remote modem does not have MNP5 capability,
the connection remains under MNP error control, but without compression.

&K0     Data compression disabled.

&K1     Auto enable/disable.  Default.  The modem enables compression if
    the serial port rate is fixed (&B1) and disables compression if
    the serial port rate follows the connection rate (&B0).  (Compression
    offers no throughput advantage when serial port and connection
    rates are equal, and may even degrade throughput.)

&K2     Data compression enabled.  Use this setting to keep the modem from
    disabling compression.

&K3     Selective data compression.  The modem negotiates only for V.42 bis
    compression, and disables MNP Level 5 (MNP5) compression.  See the
    following note.

NOTE:  MNP5 compression is not useful when transferring already compressed
files, such as the .ZIP files downloaded from Bulletin Boards and 8-bit
binary files that appear already compressed to the modem.  MNP5 tends to add
data to these files, and throughput over the phone link degrades. V.42 bis
compression detects when data is already compressed and turns off until it
detects that compression will be advantageous.  The special &K3 setting
allows the best throughput for already compressed and 8-bit binary files.


DATA RATE COMMANDS

The &Bn and &Nn commands control data rates at the serial port and phone
line interfaces.

The Sportster defaults to a fixed rate at the serial port interface (&B1)
to keep the serial port rate higher than the connection rate.  You'll get
greater throughput regardless of the connection rate.  Your software,
however, must support this feature and you must set your software to use a
fixed rate.

For the phone line, however, we recommend variable connection rates (&N0).
This lets the modem switch its connection rate to match the rate of a remote
modem, no matter what that rate is.  If the connection rate is fixed, for
example, at 9600 bps (&N6), the modem only connects with modems operating
at that rate.  Of course, if your application requires connections with
modems at only one rate, you may wish to set the modem to a fixed connection
rate.


Software Requirements

Both variable and fixed serial port rates require communications software
support.  Most communications programs support variable or fixed rates.
Check your software manual.  Set your software before making calls.


Serial Port Rate (&Bn)

Initially, the modem's serial port rate depends on your software setting.
The modem uses the rate at which it receives the AT command to determine
the serial port rate; after that it depends on its &B setting.

&B0     Variable serial port rates.  The modem switches its serial port
    rate to follow the connection rate established with a remote modem.
    If your software has Auto Baud Detect, turn it on.  The software
    will switch its serial port rate to match the connection rate.

&B1     Fixed serial port rate.  Default.  The modem detects its serial
    port rate from your last AT command and maintains it, whatever
    the connection rate.

    Set your software to 115.2K, 57.6K, 38.4K, or 19.2K bps, then set
    the modem to &B1 for the best throughput.  Some programs require
    that you turn off Auto Baud Detect to fix the serial port rate.
    Others use the term Serial Port Lock (yes or no).

    The serial port rate must equal or exceed the connection rate.
    Also, this setting requires flow control, preferably hardware (&H1),
    to avoid buffer overflow.

&B2     Fixed for ARQ calls/Variable for non-ARQ calls, Answer mode only.
    When the modem goes off hook and answers in ARQ mode, it shifts its
    serial port rate to the one written to NVRAM, for example, 38.4K bps.
    In non-ARQ mode, it acts as if set to &B0 when answering, and
    switches its serial port rate to match the call's connection rate.

    This option is designed for installations such as Bulletin Boards
    that receive calls from a wide variety of modems, ranging from the
    very slow to those with the Sportster 's advanced design.


Connection Rate (&Nn)

Use the &Nn command to select variable or fixed rates at the phone-line
interface.  Variable rates let the modem connect with a variety of remote
modems, while fixed rates limit calls to one connection rate.

&N0     Variable rates.  Default.  The Sportster negotiates with the remote
    modem for the highest possible connection rate, depending on the
    capabilities of the remote modem.  This is the recommended setting.

&N      Fixed rate.  The Sportster only connects if the remote modem is
    operating at the same rate.  If not, the Sportster hangs up.
    The fixed rate options are as follows.

&N1      300 bps
&N2     1200 bps
&N3     2400 bps
&N4     4800 bps
&N5     7200 bps
&N6     9600 bps
&N7     12,000 bps
&N8     14,400 bps
&N9     16,800 bps (V.FC/V.34 only)
&N10    19,200 bps (V.FC/V.34 only)
&N11    21,600 bps (V.FC/V.34 only)
&N12    24,000 bps (V.FC/V.34 only)
&N13    26,400 bps (V.FC/V.34 only)
&N14    28,800 bps (V.FC/V.34 only)

By fixing the connection rate, you can filter out calls at other than a
specific rate, for security or other reasons.


FLOW CONTROL

The modem uses either hardware or software flow control to manage the
amount of data stored in the buffers, thus preventing buffer overflow.

The Sportster defaults to hardware flow control.  This type of flow
control is performed between the modem and computer with serial signaling.

Software flow control uses the standard ASCII Transmit OFF (XOFF) character,
Ctrl-S, and the Transmit ON (XON) character, Ctrl-Q.

ASCII definitions are as follows.

XON     Ctrl-Q  ASCII 17 Decimal, 11 Hex
XOFF    Ctrl-S  ASCII 19 Decimal, 13 Hex

NOTE:  Both your software and computer must support the flow control you
select.  All 100% IBM PC-compatible computers support hardware flow control,
as do Apple computers equipped with a Hardware Handshaking cable.  However,
hardware flow control requires software support.  Refer to your software
documentation to see what your software supports.

When you have determined the type of flow control your system supports, be
sure to set your software appropriately before transferring files.

Warning on Software Flow Control

In ordinary operations, the only characters the modem recognizes during a
call are the three plus symbols (+++) of the escape code that return it to
Command mode.  But when software flow control is enabled, the modem or
computer also looks for Ctrl-S or Ctrl-Q characters.  If these characters
occur in a file or as part of a protocol, it reads them as XON/XOFF
characters and acts on them.

For example, XON/XOFF characters occur in binary files, and are used by
Xmodem-type protocols.  They may also come from the remote system.  An
XON from the remote system, after your modem has sent an XOFF, can result
in buffer overflow.

Software flow control may prove satisfactory if you're only transferring
text files; however, you may lose data if XON/XOFF characters occur in
the data stream from other sources.

To select software flow control, write the &F2 configuration template to Y1.

            AT &F2 &W <Enter>

Software Flow Control Precautions

If you can't use hardware flow control and are doing Xmodem-type protocol
or binary file transfers, select a protocol that performs error correction,
and turn off the modem's error control (AT&M0).

Transmit Data Flow Control (&Hn)

This type of flow control regulates data your computer transmits to the
modem for transmission over the phone link.  The modem monitors its
Transmit Data buffer as data comes in.  If the buffer nears 90% capacity,
the modem signals the computer to stop transmitting.  When it has sent
enough data over the link to empty half the buffer, it signals the computer
to resume transmitting.

When it is Required

Transmit Data flow control should be enabled in the following situations.

∙       You're using error control (any allowable rate above 300 bps),
    with or without data compression.  If data is resent due to errors,
    a continuous stream of data from the computer could overflow the
    modem's buffer.

∙       The serial port rate is higher than the connection rate.  For
    example, the serial port rate is 38.4K bps and the connection rate
    is 14.4K bps.

NOTE:  Set your software to either hardware or software flow control.
Some programs also require that you turn off the type you are not using.

&H0     Transmit Data flow control disabled.

&H1     Hardware flow control.  Default.  Your computer and software must
    support Clear to Send (CTS).  The modem drops the Clear to Send (CTS)
    signal to the computer when its buffer nears 90% capacity, and starts
    sending CTS again when the buffer is about half full.

&H2     Software flow control.  Your software must support XON/XOFF
    signaling.  The modem sends an XOFF to the terminal when its buffer
    nears 90% capacity, and sends an XON when the buffer is about half
    full.  Default in the &F2Software Flow Control template.

&H3   Use both hardware and software flow control.  Select this option if
    you're not sure what your computer supports.

NOTE:  If possible, use hardware flow control.  See Warning on Software Flow
Control, earlier in this guide for details.


Received Data Flow Control

Two commands_&Rn (hardware) and &In (software)_ control the flow of received
data passed by the modem to your computer.  Because computers handle incoming
data more quickly than the modem receives it over the phone line, most
applications won't need this.


Hardware Control (&Rn)

When your computer drops its Request to Send (RTS) signal, the modem stops
passing along received data.  The computer sends RTS again when it is ready
to receive more data. Your computer and software must support RTS.  You
cannot use this type of flow control, however, if your software requires a
constant RTS signal.

NOTE:  Use only for ARQ (error control) calls, because the V.42 and MNP
protocols control the data flow across the phone link.  During non-ARQ
calls, however, there is no way to signal the remote modem to stop sending
data.  If your modem stops passing data to your computer and the remote
modem keeps sending, the Received Data buffer will overflow.

&R0     Reserved.

&R1     The modem ignores Request to Send (RTS).  This setting is required
    if your software does not support RTS.

&R2     Hardware flow control of received data enabled.  Default.  The modem
    passes received data to your computer only on receipt of the RTS
    signal.


Software Control (&In)

When you send the modem a Ctrl-S (XOFF) command from the keyboard, the
modem stops passing received data to your computer.  When you send a
Ctrl-Q (XON) command, it resumes.

NOTE:  Because of the risk of data loss, &I15 are recommended only if
your data does not have XON/XOFF control characters.  See Warning on
Software Flow Control for details.

&I0      Disables XON/XOFF flow control of received data.  Recommended
    for non-ARQ calls.

&I1     The modem acts on your typed Ctrl-S/Ctrl-Q commands and passes
    them to the remote computer.  Not recommended for non-ARQ calls.
    Use in ARQ mode only, but keep in mind that XON/XOFF characters
    sent to the remote computer may interfere with XON/XOFF signaling
    between it and the remote modem.  &I2 is preferred for ARQ calls.

&I2     The modem acts on your XON/XOFF commands, but removes them before
    sending data to the remote computer.  Default in the &F2 Software
    Flow Control template.  Recommended setting for ARQ mode, only.
    It ensures that the remote computer does not confuse its modem's
    XON/XOFF characters with yours.

    If the call is not in ARQ mode, there is no flow control on the
    phone link.  If you send an XOFF to your modem and it stops passing
    data, it has no way to tell the remote computer and modem to stop
    sending for a while, and your modem's buffer may overflow.  See &I5
    for another alternative.

&I3     Host Mode.  Applies only to modems attached to HP mainframes using
    the ENQ/ACK protocol.  ARQ mode only.

&I4     Terminal Mode.  Applies only to modems attached to HP system
    terminals using the ENQ/ACK protocol.  ARQ mode only.

&I5     Enables phone link flow control when the connection is not under
    error control.  Both modems must use &I5.  In ARQ mode, the modem
    operates as if set to &I2.  It acts on XON/XOFF commands, but does
    not pass them on to the remote system.

    In non-ARQ mode, the modem acts as if set to &I0.  It does not look
    for local XON/OFF commands, but does look for any XON/XOFF characters
    coming in over the phone link from the remote computer.  The modem
    acts upon them and drops them from the data stream.

    Operators can signal the other modem to stop sending and control
    phone link data flow to keep their modem's buffer from overflowing,
    if both are set to &I5.


SERIAL OPERATIONS

The parameters described below are directly affected by the serial connection
and DIP switch settings, and apply to external modems only.


Carrier Detect (&Cn)

The power-on/reset default for Carrier Detect is set with DIP switch 6.
The Sportster modem is shipped with DIP switch 6 OFF, disabling override for
normal operations.

Use the &Cn command to control Carrier Detect for a current session,
independent of the switch setting.  Check your communications software
manual to find the required setting.  This command may not be stored in NVRAM.

&C0     CD override, CD always ON.

&C1     Normal CD operations.  The modem sends a CD signal when connecting
    with another modem and drops CD upon disconnecting.  Most

    communications software programs require this setting.


Data Terminal Ready (&Dn)

The power-on/reset default for Data Terminal Ready is set with DIP switch 1.
The Sportster modem is shipped with DIP switch 1 OFF, disabling override for
normal operations.

Use the &Dn command to control DTR for a current session, independent of
the switch setting.  Check your communications software manual to find the
required setting.  This command may not be stored in NVRAM.

&D0     DTR override, modem ignores DTR.

&D1     Reserved.

&D2     Normal DTR operations.  The computer or terminal must send a DTR
    signal or the modem won't accept commands.  Dropping DTR terminates
    a call.  Most communications software programs require this setting.

&D3     Reset when DTR drops (toggles).  This  command is the equivalent
    to S13=1, however it is NOT savable to NVRAM.  If you need to save
    this command to NVRAM, use S13=1


Data Set Ready (&Sn)

The modem sends your computer a Data Set Ready (DSR) signal.  (Data Set is
industry jargon for modem.)  Few, if any, commercial communications
programs require the modem to control DSR (&S1).  Leave the modem set for
DSR override (&S0), unless you know that your installation requires a
different setting.

&S0     DSR is always ON (override).  Default.

&S1     In Originate mode, the modem sends DSR after dialing, when it
    detects the remote modem's answer tone.  In Answer mode, it sends
    DSR after sending an answer tone.


GETTING HELP

Checking the Help screens is the first step to recovery.  These screens give
you the information you'll need to identify a problem.  Once a problem is
identified, it can easily be solved.


INQUIRIES (In)

The Inquiry command has eight options.  The most commonly used options
display the following information.

    ATI4    Current settings
    ATI5    NVRAM settings
    ATI6    Link diagnostics

I0      The modem returns a product code.  If you have a problem and call
    U.S. Robotics' Technical Support Department, you may be asked for
    this product code.

I1      The modem performs a checksum of its read-only memory (ROM) and
    returns the result to the screen.  This function is used only in
    factory testing.  The modem should always read the same number.

I2      The modem performs a test of its random-access memory (RAM) and
    returns either the OK (0) or ERROR (4) result code, followed by OK
    when the test is completed.  You may want to use this command
    as a checkpoint if the modem appears to be malfunctioning.

I3      The modem returns a product identifiication string.

I4      The modem displays its current configuration.

I5      The modem displays the stored phone numbers and two templates (Y0
    and Y1) stored in nonvolatile random access memory (NVRAM).
    Activate the second screen by pressing any key.

I6      During a connection, the modem monitors and stores information about
    link operations.  When the call is ended, you can request a
    diagnostic summary.

    For calls under data compression, the number of characters sent may
    be less than the number of octets sent, due to buffering operations.

    Most terms used in the display are self explanatory except for
    the following:

        Octets:  Compressed data units.  If the number of octets is
        greater than the  number of characters sent, the modems
        probably used MNP5 compression on an already compressed file,
        and the result was expanded data.

        Blers:  Errors in data and protocol blocks.  If there were
        many block errors, your receiver may have experienced
        problems on the line.

        Blocks Resent:  These represent blocks the remote modem
        resent due to the previous category, Blers.

        Link Timeouts:  Protocol detection problems; communications
        were severed momentarily and the modems probably recovered.
        This does not indicate the retry timeout.

        Link Naks:  Negative acknowledgments (one or more blocks).

        Data Compression:  Indicates the type of data compression
        negotiated for the call (V42BIS or MNP5) or NONE.  A V42BIS
        response includes the size of the dictionary and the maximum
        string length used, for example, 2048/32.

        Fallback: Enabled/Disabled:  indicates whether or not the
        modems negotiated online fallback during the connection
        sequence.

        Protocol:  Indicates the error control protocol negotiated
        (LAPM, MNP, NONE).

        Speed:  The last rates at which the  receiver/transmitter
        were operating before disconnecting.

        Disconnect Reason:  Possible reasons the modem hung up are
        as follows:

        DTR dropped--The DTE dropped the Data Terminal Ready signal,
        terminating the call.

        Escape code--The operator sent the modem the +++ escape code.

        Loss of carrier--The modem detected loss of the remote
        modem's carrier and waited the duration specified in
        Register S10 (default is 0.7 seconds).

        Inactivity timeout--The modem detected no activity on the
        line for the duration specified in Register S19 (default
        is 0, timer disabled).

        MNP incompatibility--The modem is set to &M5 and the remote
        modem does not have MNP compatibility, or there was an MNP
        negotiation procedure error.

        Retransmit limit--The modems reached the maximum of 12
        attempts to transfer a data frame without error.

        LD received--The remote modem sent an MNP error control Link
        Disconnect request.

        DISC--The remote modem sent a V.42 Disconnect frame.

        Loop loss disconnect--The modem detected a loss of current
        on the loop connecting it with the telephone company central
        office.  This usually occurs because the remote modem has
        hung up:  the central office drops current momentarily when
        there is a disconnect at the other end of a call.  Unless
        Register S38 is set higher than 0, the modem immediately
        hangs up at loop loss.

        Unable to retrain--After several attempts, disturbances on
        the phone line prevented the modems from retraining
        (resynchronizing), and they could no longer transmit or
        receive data.

        Invalid speed--The modem is set to &N1 or higher, for a
        fixed link rate, and the remote modem is not operating at the
        same rate.

        XID timeout--The modems failed to negotiate the V.42
        Detection (XID Exchange) phase.

        SABME (Set Asynchronous Balance Mode Extended) timeout--The
        modems failed this part of V.42 link negotiation.

        Break timeout--Incompatible processing of a Break signal
        occurred.

        Invalid codeword--The modem received an invalid V.42 bis
        (compression) frame.

        A rootless tree--The modem received an invalid V.42 bis
        (compression) frame.

        Illegal command code--The modem received an invalid V.42 bis
        (compression) frame.

        Extra stepup--The modem received an invalid V.42 bis
        (compression) frame.

I7      The modem returns a product configuration.  If you have a problem
    and call U.S. Robotics' Technical Support staff, you may be asked
    to read this screen.


S-REGISTER QUERY (SR?)

This command allows you to view the contents of a particular S-Register,
as in the following example that requests the contents of Register S0
("On what ring will the modem answer?").

            ATS0? <Enter>

STORED PHONE NUMBER QUERY (&Zn?)
At this command, the modem returns the phone number stored in NVRAM at
position n, as in the following example that includes a sample modem response.

            AT&Z3? <Enter>
            5551234

LAST-DIALED NUMBER QUERY (DL?)
At this command the modem displays the number stored in the last-dialed
number buffer.
            ATDL? <Enter>

HELP SCREENS

Sportster modems provide four Help screens:  summaries of the basic AT
command set, extended ampersand (&) command set, Dial command options,
and S-Register functions.

Stop/Restart Display
    The following command stops the display.  Hold down the Control
    key and type S.

            <Ctrl>-S

    To restart the display, use the same command or press <any key>.

Cancel Display

    Either of the following commands cancels the display.

            <Ctrl>-C
            <Ctrl>-K


Basic Command Set ($)

At AT$, the Sportster displays a screen that shows a partial summary of
the command set.  A second screen, activated by pressing any key, shows
the remaining commands.


Ampersand Command Set (&$)

At AT&$, the Sportster displays a screen that shows a partial summary of the
extended ampersand command set.  A second screen, activated by pressing any
key, shows the remaining command set.


Dialing (D$)

At ATD$, the Sportster displays the Dial command summary.


S-Register Functions (S$)

At ATS$, the Sportster displays a screen that shows a partial summary of
the S-Register functions.  A second screen, activated by pressing any key,
shows the remaining registers.




            TESTING THE MODEM

Modem testing is available with the &Tn command and Register S16 (Dial test).
All loopback testing conforms to ITU-T Recommendation V.54.

NOTE:  Only one test can be performed at a given time.  If you send a test
command while the modem is in Test mode, you'll receive an ERROR message.


TESTING WITH &Tn

The tests supported through the &Tn command include Analog Loopback, Digital
Loopback, and Remote Digital Loopback.  You can key in your own data during
testing, or use the modem's internal test pattern and error detector.

Always disable error control before testing.  If the modem is detecting
errors and retransmitting the affected data, your test results will be
invalid.


Ending a Test_&T0, S18

Issue the &T0 command to terminate a test.  Alternatively, set Register S18
to a specified number of seconds, for example, S18=10.  When the 10 seconds
are up, the modem automatically ends the test and returns to Command mode.
If the test was Analog Loopback, the &T0 command hangs the modem up.  If the
test was Digital or Remote Digital Loopback, issue an ATH command to hang up
the modem, or an ATZ command to hang up the modem and reset it to its
defaults.

NOTE:  If you use the S18 test timer, but in the process of testing you
issue an ATZ command, S18 resets to zero and the timer is disabled.  Also,
you cannot store a value for S18 in nonvolatile memory;  its power-on and
reset default is always zero.


Analog Loopback_&T1, &T8

This test checks the operation of the modem's transmitter and receiver.

 &T1

This AL option requires that you type data you can later verify at your
screen.

1.      The modem should be on hook in Command mode.  If you wish, set
    Register S18 as a test timer.  For example, insert S18=10 in the
    following command string before &T1.

            AT &M0 S18=10 &T1 <Enter>

The modem disables error control, sets the timer, enters Analog Loopback
(AL) mode, and sends a CONNECT message.

2.      Type recognizable data so that you can verify it when it is looped
    back to the screen.

3.      End the test.  If you set S18, the modem automatically stops the
    test at the timeout, exits AL mode and responds OK.

    If you didn't set Register S18, wait one second and type +++ to end
    the test and return the modem to Command mode.  When the modem
    responds OK, type AT&T0 to terminate AL mode and hang up the modem.
    (Typing ATH has the same effect.  Typing ATZ also has the same
    effect, but also resets the modem and restores your &M default.)

    The modem responds OK.  If the modem sends an ERROR message, you
    have issued an invalid command.

4.      If there were no errors, reset the modem to &M4, for error control,
    unless you've issued the ATZ reset command.

    NOTE:  If the modem is in Online-Command modethat is, still connected
    to a remote modemand you send it an &T1 or &T8 command, it drops the
    call, enters AL mode, sends a CONNECT result and waits for loopback
    characters.
&T8

This AL option causes the modem to send an internal test pattern to its
transmitter and loop it back to the receiver.  An internal error detector
counts any errors and, when the test is ended, sends the number of errors or
000 (no errors) to the screen.

Since you don't type anything during this test, and the modem does not send
anything to the screen, this option verifies only the modem.  If there are
no errors but your problem continues, it may be at the computer interface.

1.      The modem should be on hook in Command mode.  If you wish, set
    Register S18 as a test timer.  For example, insert S18=10 in the
    following command string before &T8.

        AT &M0 S18=10 &T8 <Enter>

    The modem disables error control, sets the timer, and enters AL mode.
    The modem sends its internal test pattern to the transmitter, and
    loops the pattern back to the receiver.  You will not see any data
    on your screen.

2.      End the test.  If you set S18, the modem automatically stops the
    test at the timeout.  If you didn't set Register S18, type AT&T0 to
    end the test.  Or use ATH or the command that resets the modem, ATZ.
    Both of the latter end the test and hang up the modem.

    When the modem hangs up, it returns a three-digit code, followed by
    OK.  A code of 000 indicates no errors were found.  A code of 255
    indicates 255 or more errors.  An ERROR message indicates that you
    issued an invalid command.

3.      If there were no errors, reset the modem to &M4 for error control
    unless you issued the ATZ command.

&T2

This option is reserved.


Digital Loopback--&T3

If your modem has passed the Analog Loopback (AL) test, this test can help
you locate a problem with a remote modem or the telephone channel.

1.      Set the modem to &M0 to disable error control.  Establish a
    connection with the remote modem.

2.      Bring the modem back to Online-Command mode with the +++ escape code.
    Then send it the AT&T3 command.  The modem enters Digital Loopback
    (DL) mode.

3.      The remote user should type a short message.  It will be looped back
    by your modem's transmitter for verification on the remote screen.
    You will not see the message or any other data.

4.      When the remote user has completed the test,  issue the AT&T0 command
    to end the test.  If you wish, return the modem online (ATO) to
    resume Data mode.  Or type either ATH or the command that resets the
    modem, ATZ.  The latter two commands end the test and hang up the
    modem.  The modem responds OK.  If the modem sends an ERROR message,
    you have issued an invalid command.

&T4, &T5

The &T4 option grants a remote modem's request for a Remote Digital Loopback
test.

The &T5 option cancels &T4 and your modem will not recognize a request for
a Remote Digital Loopback test from a remote modem.  This is the default so
that your modem isn't subject to another user calling and tying up your
modem without your permission.


Remote Digital Loopback--&T6, &T7

This test, like the Local Digital Loopback test, verifies the condition of
both modems and the phone link.

The request for and granting of Remote Digital Loopback testing requires that
both modems use ITU-T V.54 standard signaling.  The test must be performed
at 2400 or 1200 bps.  If the remote modem does not have the capability or is
not set to respond, you will get an ERROR result code.

&T6

This RDL option requires that you send keyboard data to the modem and verify
it when it is returned over the phone lines and to your screen.

1.      Set your software to 2400 or 1200 bps.  Set the modem to &M0.  If you
    wish, set the S18 timer. Establish a connection with the remote
    modem.  If you haven't already done so, arrange with the remote user
    to cooperate with your testing.  The remote user should set his or
    her modem to acknowledge the RDL request, for example, AT&T4.

2.      Bring the modem back to Online-Command mode with the +++ escape code.
    Send it the AT&T6 command.  The modem enters RDL mode.

3.      Type a short message.  It will be looped back to your modem by the
    remote modem and to your screen for verification.  (The remote user
    will not see your data.)

4.      End the test.  If you set Register S18 the modem automatically ends
    the test when the test timeout is reached.  If you didn't set S18,
    type AT&T0 to end the test.  If you wish, return the modem online
    (ATO) to resume Data mode.  Or send either ATH or the command that
    resets the modem, ATZ.  The latter two commands end the test and hang
    up the modem.  The modem responds OK.  If you issue an invalid
    command, the modem sends an ERROR message.

    Data errors indicate a problem with the remote modem or the phone
    link.  If you have not performed analog loopback testing with your
    modem, the problem may also lie with your modem.

5.      Reset the modem to &M4 unless you used the reset command, ATZ.

&T7

This test option causes the modem to send an internal test pattern through
the Remote Digital Loopback.  An internal error detector counts any errors
and, when the test is ended, sends the number of errors or 000 (no errors)
to the screen.

You don't need to type anything during this test.  The modem sends only its
final error count to your screen.

1.      Set your software to 2400 or 1200 bps.  Set the modem to &M0.  If
    you wish, set the S18 timer. Establish a connection with the remote
    modem.  If you haven't already done so, arrange with the remote
    user to cooperate with your testing.  The remote user should set his
    or her modem to acknowledge the RDL request, for example, AT&T4.

2.      Bring the modem back to Online-Command mode with the +++ escape code.
    Then send it the AT&T7 command.  The modem enters RDL mode. The modem
    sends its internal test pattern to the remote modem, which loops it
    back to your modem.  You will not see the data on your screen.

3.      End the test.  If you set S18, the modem automatically stops the test
    when the timer times out.  If you didn't set Register S18, type AT&T0
    to end the test.  After you view the test results (next paragraph),
    return the modem online if you wish (ATO) and resume Data mode.  Or
    send either ATH or the command that resets the modem, ATZ.  The
    latter two commands end the test and hang up the modem.

    When you terminate the test, the modem returns a three-digit code,
    followed by OK.  A code of 000 indicates no errors were found.  A
    code of 255 indicates 255 or more errors.  If you issue an invalid
    command, the modem sends an ERROR message.

    If you've performed an Analog Loopback and know your modem is working
    properly, errors indicate a problem with either the phone connection
    or the remote modem.

4.      Reset the modem to &M4 unless you've sent it the ATZ reset command.


DIAL TEST_S16=2

The Dial test is used for factory-testing the frequencies of tone dialing
values.  When S-Register 16 is set to 2 and a single tone is dialed (for
example, ATD7 <Enter>), the modem continues to transmit that tone until
you press Enter again.




            OTHER OPERATIONS


FAX OPERATIONS


Fax Modem Guidelines

Fax operations require facsimile-compatible software that can send or
receive Group III faxes.  Follow the instructions in your fax software
manual.

The modem's normal operating mode is Data mode.  If your fax software is
typical, it automatically switches the modem to Fax mode when you run the
program, and resets the modem to Data mode when you exit the program.

If you have a problem, however, and think the modem may be in the wrong mode,
you can use one of the following AT commands to manually switch the modem.

Most users will never need to use these commands.

        AT+FCLASS=0 <Enter> (Switch to Data mode)
        AT+FCLASS=1 <Enter> (Switch to Class 1 Fax mode)
        AT+FCLASS=2.0 <Enter> (Switch to Class 2.0 Fax mode)

If you are not sure whether the modem is in Data or Fax mode, type the
following command.

            AT+FCLASS? <Enter>

The modem returns a 0 to indicate Data mode, a 1 to indicate Class 1 Fax
mode or a 2.0 to indicate Class 2.0 Fax Class mode.  Sportster modems are
not compliant with TR-29 (SSP-2388-A)  Class 2 facsimilie control.

NOTE:  Whenever the fax modem is reset using the ATZ command, toggling the
DTR signal, or turning the power off and on, the modem will be set to Data
mode.


Fax Mode Flow Control Setting

Many facsimile software products use software flow control when the modem
is in Fax mode.  To allow compatibility with software products that use
software flow control by default, U.S. Robotics fax modems switch to software
flow control when entering Fax mode.

For the best information on modem settings, see your Fax software manual.


FCC Notice

FCC part 68, rules regarding fax operation, has been amended as follows:

    Telephone facsimile machines_identification of the sender of the
    message:  It shall be unlawful for any person within the United
    States to use a computer or other electronic device to send any
    message via a telephone facsimile machine unless such a message
    clearly contains, in a margin at the top or bottom of each
    transmitted page or on the first page of the transmission, the
    date and time it is sent and an identification of the business,
    other entity, or individual sending the message and the telephone
    number of the sending machine or of such business, other entity, or
    individual.  Telephone facsimile machines manufactured on and after
    December 20, 1992 must clearly mark such identifying information on
    each transmitted page.


A Note to Programmers

If you want to know more about the supported fax commands, refer to the
standard for the Service Class 1 fax protocol.

    ANSI/EIA/TIA-578-1990 (EIA-578)
    Asynchronous Facsimile DCE Control Standard
    November, 1990  Approved:  October 22, 1990

You can obtain a copy of this standard by contacting Global Engineering
Documents, at  1-800-854-7179 or 303-792-2181 or by fax at 303-843-9880.

For more information on supported Class 2.0 fax commands, refer to the
standard for the Service Class 2.0 fax protocol.

    ANSI/EIA/TIA-592-1993 (EIA-592)
    Asynchronous Facsimile DCE Control Standard
    May, 1993


VOICE/DATA COMMUNICATIONS

When you install the Sportster, you have the option of plugging your phone
into the second modular jack of the modem so it's available for voice calls.
You can also use the phone to set up communications with another user whose
modem uses the AT command set, such as a U.S. Robotics or U.S. Robotics-
compatible modem.

NOTE:  If the modem is off-hook, the handset will appear to be dead, no sound
will be heard through the handset.


Preparation

First call the other user to establish the parity, word length, and number
of Stop bits the other person's modem accepts.  Then turn the call over to
your modems, as follows.


Procedures

1.      Without hanging up the phone, have your modem go off hook in
    Originate mode.  Type the following command.

            ATD <Enter>

NOTE:  Be sure the modem is not set to X2 or X4, or it will return the
NO DIAL TONE result code and hang up.

2.      The other party should have the remote modem go off hook in Answer
    mode.  The following command is used to do this.

            ATA <Enter>

3.      Now both of you can hang up your respective phones while the two
    modems establish the data link.  They will maintain the link until
    one of you gives your modem a command to disconnect. Either party's
    device can be the originate or answer modem; it doesn't matter who
    made the phone call.  But one modem must enter Originate mode and
    the other Answer mode.  You and the other party, therefore, must
    agree on which command, ATD or ATA, you will each use.




TECHNICAL SPECIFICATIONS


COMPATIBILITY

The Sportster modem conforms to the following standards, ensuring
compatibility with a wide base of installed modems.  ITU-T is the new
signifier of what was formerly the CCITT international standards body.

V.34            28.8K/26.4K/24K/21.6K/19.2K/16.8K/14.4K/12K/9600/
        7200/4800  /2400 bps (V.34 only)

V.Fast Class    28.8K/26.4K/24K/21.6K/19.2K/16.8K bps (V.FC/V.34 only)

ITU-T V.32 bis  14.4K/12K/9600/7200/4800 bps (14,400 modems only)

ITU-T V.32      9600/4800 bps

ITU-T V.22 bis  2400 bps

Bell 212A       1200 bps (also ITU-T V.22)

ITU-T V.23      1200 bps with 75 bps back channel (Some United Kingdom and
        European phone systems)

Bell 103        300 bps (ITU-T V.21 optional)

ITU-T V.42      LAPM error control, 1200 bps and higher


ITU-T V.42 bis  Data compression, 1200 bps and higher

MNP             Levels 2, 3 and 4 error control, level 5 data compression,
        1200 bps and higher

ITU-T V.54      Analog, digital, and remote digital loopback testing


Fax Modems

EIA/TIA-592     Service Class 2.0 Asynchronous Facsimile DCE Control Standard (V.FC/V.34 only)

EIA/TIA-578     Service Class 1 Asynchronous Facsimile DCE Control Standard

ITU-T V.17      14.4K/12K bps

ITU-T V.29      9600/7200 bps

ITU-T V.27 ter  4800/2400 bps

ITU-T V.21      300 bps


THE SERIAL INTERFACE

The serial interface information below applies only to external modems.


Description

The serial interface is a standard developed by the Electronic Industries
Association (EIA).  It defines the signals and voltages used when data is
exchanged between a computer and a modem or serial printer.

The entire standard covers many more functions than are used in most data
communications applications.  Data is transmitted between the devices over
a shielded serial cable with a 25-pin male (DB-25P) connector to the modem
and a 25-pin, 9-pin, 8-pin, or custom-built connector to the computer.

NOTE:  FCC regulations require the use of a shielded cable when connecting
a modem to a computer to ensure minimal interference with radio and
television.


Pin Assignments

Pin assignments are factory-set in the Sportster modem to match the standard
DB-25 assignments in the following table.  DB-9 connectors for IBM
PC/AT-compatible computers should be wired at the computer end of the cable
as shown in the DB-9 column.


            Serial Interface Pin Definitions

                        Signal Source

    DB-25   DB-9    Circuit Function        Computer _ Modem
    1       -       AA      Chassis Ground          Both
    2       3       BA      Transmitted Data        Computer
    3       2       BB      Received Data           Modem
    4       7       CA      Request to Send         Computer
    5       8       CB      Clear to Send           Modem
    6       6       CC      Data Set Ready          Modem
    7       5       AB      Signal Ground           Both
    8       1       CF      Carrier Detect          Modem
    12      -       SCF     Speed Indicate          Modem
    20      4       CD      Data Terminal Ready     Computer
    22      9       CE      Ring Indicate           Modem

NOTE:  A three-wire interface consists of Receive, Transmit, and Ground wires and does not support hardware flow control.  Systems requiring three-wire interfaces
must use software flow control.  If your system doesn't support software flow
control, use no flow control but be sure to use an error-correcting protocol.

If you're using a Macintosh computer, ask your dealer for the correct modem
cable; we recommend a Hardware Handshaking cable. (This cable is included
with the Sportster Mac&Fax modem)

            Macintosh 8-Pin DIN
                            Signal Source
    DB-25   MAC     Function                        Computer _ Modem
    20/5@   1       Output Handshake@               Computer/Modem@
    4       2*      Input Handshake                 Computer
    2       3*      Transmit Data Negative+         Computer
    7       4       Ground                          Both
    3       5       Receive Data Negative#          Modem
    -       6       Transmit Data Positive          -
    -       7       Not connected                   -
    -       8       Receive Data Positive           -

@  Adds CTS capability when in Hardware mode.
*  Hardware handshaking lines.
+  To do this, you must ground pin 6.
#  To do this, you must ground pin 8.

Minimum RequirementsSome computer equipment supports only a few of the serial
signal functions set in the Sportster modem.  The minimum required for the
modem to operate is as follows.

            Minimum Required Pins

    DB-25   DB-9    8-Pin
    Pin     Pin     DIN     Function
    2       3       3       Transmitted Data
    3       2       5       Received Data
    7       5       4       Signal Ground
    20      4       1       Data Terminal Ready*

* Required if DIP switch 1 is OFF for normal DTR operations, override disabled.


Additional Flow Control Functions

If your computer and software support Clear to Send (CTS) and you wish to use
Transmit Data hardware flow control (&H1), Pin 5 (DB-25) or Pin 8 (DB-9) is
required.

If your computer and software support Request to Send (RTS) and you wish to
use Received Data hardware flow control (&R2), Pin 4 (DB-25) or Pin 7 (DB-9)
is required.

For 115.2K, 57.6K and 38.4K bps Serial Port Rates

    Your software and computer must support the 115.2K, 57.6K or
    38.4K bps rate.  Make sure the serial cable is shielded.
    Cables are normally six feet long, but longer lengths are possible.
    If you encounter problems with signal degradation, try a shorter
    cable.

    If you decide to build your own cable, use a low-capacitance cable.
    To further minimize the capacitance, connect only those functions
    (pins) that your application requires.

    NOTE:  Only V.FC and V.34 modems will support a rate of 115.2K bps.


DEFAULT SETTINGS

Data Format
Both your software and the remote system must use the same 10-bit data
format.  If you don't know the setup of the remote computer's modem, phone
ahead to find out what combination of word length, parity, and Stop bit is
required.

Set your communications software to the required scheme.  Some
communications programs use a kind of shorthand for formats, such as
7-E-1 or 8-N-1.  The modem detects the format from the AT prefix of the
next command it receives from your keyboard or from your software.

            Allowable Data Formats

            Word    Parity  Stop
            Length  (1 Bit) Bits
            7       Even, Odd,      1
                Mark, Space
            7       None            2
            8       None            1

Template Settings

You can create one or two customized configurations and store one of them
at a time in nonvolatile random-access memory (NVRAM) as your power-on/reset
default using the &Wn command.  As long as DIP switch 7 is OFF when you
power-on or reset the modem, your defaults are loaded into the modem's
random-access memory (RAM).  To view your NVRAM settings, use the ATI5
command.

The Sportster modem is preconfigured in the factory for the &F1 Hardware Flow
Control template settings in NVRAM as Y0, and the &F2Software Flow Control
template settings in NVRAM as Y1.

Tables on the next pages list the settings of the permanent configuration
templates &F1 (default), &F2, and &F0, as well as parameters you can modify
and store in the NVRAM configuration templates.

        &F1--Hardware Flow Control Template
            Factory Default

Feature                         &F1 Settings

ITU-T/Bell Answer Sequence              B0      ITU-T sequence
Online Echo                             F1      Online Echo OFF
Speaker Control                         M1      Speaker ON until CONNECT
Pulse/Tone Dialing                      P       Pulse Dialing
Result Code Options                     X4      All Result codes
ARQ Result Codes                        &A3     All protocol codes enabled
Serial port Rate                        &B1     Fixed serial port rate
Guard Tone                              &G0     No guard tone
Transmit Data Flow Control              &H1     Hardware flow control
Modem Testing                           &T5     Deny remote digital loopback
Received Data Hardware Flow Control     &R2     Enabled
Received Data Software Flow Control     &I0     Disabled
Data Compression                        &K1     Auto enable/disable
Error Control                           &M4     Auto select
Connection Rate                         &N0     Variable connection rate
Make/Break Ratio                        &P0     U.S./Canada ratio
Volume Control (internal)               L2      Medium volume
Data Set Ready (DSR)                    &S0     DSR always on
Break Handling                          &Y1     Break clears buffer; break
                        then  goes to remote modem

The following parameters are changed via your communications software:

    Stored Phone Numbers    &Zn=s
    Word Length             8 bits*
    Parity                  None*
    Serial port Rate        19.2 kbps*

* Initial Settings; match software settings of subsequent &W commands.

The &F2 and &F0 templates largely resemble the &F1 template.  The tables
below list only those settings that differ from the &F1 template.

        &F2 Software Flow Control Template

    Feature                         &F2 Setting

    Transmit Data Flow Control      &H2 Transmit data software flow
                        control
    Receive Data Flow Control       &R1 Received data hardware flow
                        control disabled
                    &I2 Received data software flow
                        control enabled


        &F0 Low Performance Template

    Feature                         &F0 Settings

    Result Code Options             X1  Basic subset
    ARQ Result Codes                &A1 ARQ codes enabled
    Serial port Rate                &B0 Variable serial port rate
    Transmit Data Flow Control      &H0 Disabled
    Receive Data Flow Control       &R1 Disabled

The following parameters are changed via your communications software:

Word Length             7 bits*
Parity                  Even*
Serial port Rate        9600 bps*

* Initial Settings; match software settings of subsequent &W commands.

            NVRAM S-Register Options

    NVRAM S-Register Options                Factory Setting

    S0*     Number of rings to answer on            1
    S2      Escape code character                  43
    S3      Carriage Return character              13
    S4      Line Feed character                    10
    S5      Backspace character                     8
    S6      Dial wait-time, sec.                    2
    S7      Carrier wait-time, sec.                60
    S8      Dial pause, sec.                        2
    S9      Carrier Detect time, 1/10th sec.        6
    S10     Carrier loss wait-time, 1/10th sec.     7
    S11     Tone duration, spacing, msec.          70
    S12     Escape code guard time, 1/50th sec.    50
    S13     Bit-mapped functions                    0
    S14     Bit-mapped functions                    0
    S15     Bit-mapped functions                    0
    S19     Inactivity/hang up timer                0
        S21     Break length, 1/100th msec.    10
    S22     XON character                          17
    S23     XOFF character                         19
    S25     DTR recognition time, 1/100th sec.      5
    S27     Bit-mapped functions                    0
    S28     V.21/V.23 fallback delay, 1/10th msec.  8
    S34     Bit-mapped functions                    6
    S38     Disconnect wait time, sec.              0
    S51     Bit-mapped functions                    0    (V.FC/V.34 only)
    S54     Bit-mapped functions                    0    (V.FC/V.34 only)
    S55     Bit-mapped functions                    0    (V.FC/V.34 only)
    S56     Bit-mapped functions                    0    (V.FC/V.34 only)


NOTE:  Bit-mapped registers have up to eight functions.  See instructions
under S13 in Appendix A of the Quick Installation Guide.

* The valid range of rings that can be stored in NVRAM for S0 is 1-255.
S0=0 cannot be stored in NVRAM.  Regardless of the NVRAM setting, DIP
switch 5 must be OFF for the modem to be in Auto Answer mode at
power-on/reset.



            MODEM CONCEPTS


HOW MODEMS WORK

Modem is a term based on the concept of modulation and demodulation.  A
modem modulates (converts) digital data (computer information) to analog
data (fluctuations in tones carried over a copper telephone wire).  The
information is carried over a telephone network until it reaches its
destination, where another modem demodulates the analog signals and
converts them back to digital data so the computer there can use the
information.

This ability to use the telephone network for quick, inexpensive data
exchange is a powerful tool used by businesses and individuals worldwide
to expand business and personal networks.


MODEM CONFIGURATION

Modems come in all shapes and sizes and their ability to communicate is
based on the protocols they use, or rules they follow to perform operations
in identical ways.  They may be preset or reset physically (DIP switches)
and logically (communications software) to best communicate with the modem
they are transferring information to and receiving information from.

Much of this is done automatically by the modems when they initially contact
each other.  The calling modem contacts the answering modem and introduces
itself.  The modems communicate via a series of signals to identify the
appropriate protocol and speed for efficient data transfer.  The answering
modem either accepts the call or rejects the call.  This transaction is
called a handshake.

Successful handshaking results in what is called carrier.  When modems
establish carrier, your modem sends a Carrier Detect signal to your
computer, indicating that the modems are ready to transfer data.  If
they fail to connect, your modem sends your computer a No Carrier message.


LINE TRAVEL

Poor line quality may cause a decrease in efficient data transmission.  In
order to ensure the data sent and received is reliable, error control was
introduced by modem manufacturers.  The modems check each data block
received, and if something went wrong between locations, the receiving
device instructs the sending device to resend the affected block.

Modems send information at different rates, measured in bits per second
(bps).  Today,  the figures can be staggering.  In the most optimal
situation, the Sportster can exchange data as fast as 115,200 bps.

In most cases, though, the speed relies heavily on the ability to adapt to
line conditions at high speed.  This adaptability is the most important
feature of the Sportster.


DIGITAL DATA

Modems send data via asynchronous communication.  The smallest data unit
sent is made up of a defined word length (7 or 8 bits each), a Start bit
(a 0 that indicates where the data unit begins), and one or two Stop bits.

Parity bits were the typical method of controlling errors before cyclic
redundancy check (CRC) error correction, described below under Error Control.
A parity bit is either a 1 (odd parity) or a 0 (even parity), depending
upon whether the data segment has an odd or even number of binary digits.
Some systems allow mark parity (parity is always 1odd) or space parity
(parity is always 0 even).  Parity bits are used less often now that CRC
is common.

The setting 8-N-1 (word length=8, parity=None, stop bits=1) has become
the most common data format in data communications.  Both computers
involved in a data transfer must use the same parity, word length, and
number of Stop bits or connection isn't possible and garbage characters
will display.  The software must first be set the same on the computers at
both ends of the data transfer before the modems can operate effectively.
A simple phone call to determine the settings at the other end can clear
this up quickly and easily.

The requirement to specify parity setting, even if it is None (8-N-1),
assures that users with older systems can still communicate with newer modems.


FLOW CONTROL

Another important aspect of modem communications is flow control, which
manages the amount of data stored in buffers.  Buffers are used to store
information temporarily before it is passed on to a computer or modem.
Flow control is used to prevent buffer overflow.  The system uses either
hardware or software (control characters) flow control.  U.S. Robotics
recommends the use of hardware flow control, because actual data may be
mistaken for the control characters used in software flow control and
the data may be distorted.


ERROR CONTROL

Error control protects the integrity of data transferred over phone channels
and is available for calls at 1200 bps and above.  It can be disabled,
although high-speed calls (above 2400 bps) should always be under error
control.  The operations defined in an error control protocol include
the following.

∙       Establishment of compatibility

∙       Data formatting into blocks

∙       Error detection through Cyclic Redundancy Checking (CRC)
    CRC is based on algorithms that calculate a value for an entire
    block of data.  The CRC value attached to each block sent must match
    the receiving modem's calculation.  If not, the remote modem sends a
    negative acknowledgment to the sending modem.

∙       Positive acknowledgment of error-free blocks and negative
    acknowledgment of corrupted data blocks

∙       Retransmission of corrupted data blocks

Always set the Sportster for error control, &M4 (default) or &M5, for calls
at speeds over 2400 bps.  Most users communicating with V.42- or
MNP-compatible modems will want error control at 2400 and 1200 bps, as well.

The Sportster is set at the factory to &M4, causing it to try for an error
control connection and, if that isn't possible, to proceed with the call in
Normal mode.  The modem first tries for a V.42 connection, then an MNP
connection.  The information below is based on the Sportster's setting of &M4.


ITU-T V.42 Handshaking

The exchange of signals between two devices in order to establish a
communications link is called handshaking.  ITU-T V.42 includes a two-stage
handshaking process.

∙       A Detection phase that is based on an exchange of predefined
    characters.

∙       LAPM (Link Access Procedures for Modems) Negotiation.  In this
    phase, the modems identify their capabilities concerning maximum
    data-block size and the number of outstanding data blocks allowed
    before an acknowledgment is required.


MNP Handshaking

This protocol is supported by the ITU-T V.42 Recommendation.  It was
originally developed by Microcom, Inc., and is now in the public domain.

MNP handshaking begins with an MNP Link Request sent by the calling modem.
If the remote modem doesn't recognize the request, error control isn't
possible.


Data Compression

If the modems successfully establish a V.42 connection, they also negotiate
for V.42 bis data compression.  If they successfully establish an MNP
connection, they negotiate for MNP5 data compression.

Modems using V.42 bis compression negotiate the following options.

∙       Dictionary size--that is, the amount of memory available for
    compression table entries.  (Entries are codes devised for
    redundant data.  The data is packed into shorter data units,
    called code words, and unpacked by the receiving modem.)
    Possible sizes are as follows.  U.S. Robotics modems use 11-bit, or
    2048-entry dictionaries, but drop down if the remote modem uses a
    512- or 1024-entry dictionary.

    Bits    Entries

    9       512
    10      1024
    11      2048

∙       Maximum string length of each entry.

As the dictionary fills, the modem deletes the oldest unused strings.
V.42 bis compression is more efficient than MNP5 compression, in part
because it dynamically deletes unusable strings.  In addition, it works
better with files that are already compressed.  These include .ZIP files
downloaded from many Bulletin Boards and 8-bit binary files, which appear
to the modem to be compressed. MNP5 compression should not be used with such
files because it adds data to them, which lessens throughput.  (The
additional data is stripped when the file is decompressed by the remote
modem.)  When transferring such files, it's best to set the modem to &K3.
This allows V.42 bis compression to work dynamically with the compressed
data, but disables MNP5.


Flow Control

Flow control of data from the computer is required under error control for
two reasons.
    1.      The transmitting modem buffers a copy of each frame it
        transmits to the remote end until it is acknowledged by
        the receiving modem.

    2.      If errors are encountered, the transmitting modem must
        resend the corrupted data.  This retransmission activity,
        combined with the steady stream of data from the computer,
        can overflow the buffer.


Online Fallback/Fall Forward

Under error control, if a disturbance on the phone line causes an error to a
data block, the receiving modem replies with a negative acknowledgment.  In
response, the transmitting modem retrieves a copy of the original data block
from its Transmit buffer, and every block it sent after that block, and
retransmits them.  This keeps the data error-free and in sequence.

However, there is a retransmit limit:  the modems hang up if line
disturbances are so severe that one of the modems has retransmitted the
same block of data twelve times without a positive acknowledgment.

Because high-rate calls are more vulnerable than transmissions at 2400 bps
and below, V.32 bis/V.FC modems risk reaching the retransmit limit and
hanging up.  To prevent this, one of the modems requests that they fall back
if necessary.  When line conditions improve, the modems fall forward to the
next higher rate, up to the link rate of the call.

Online fallback/fall forward is defined in V.FC and ITU-T recommendation
V.32 bis for modems.  The Sportster 9600, however, is a V.32 modem.
V.32 modems fallback to 4800 bps and stay at that rate.


THROUGHPUT GUIDELINES

The following guidelines should help you to make the most of your modem's
advanced performance features.  In many instances, experimentation and
experience will indicate what works best for your applications.

Throughput is the volume of user information transferred per second, without
Start and Stop bits and other overhead information.  You'll obtain optimal
throughput under the following conditions.

1.      Your communications software supports a fixed serial port rate higher
    than the connection rate (for example, setting your software to lock
    into the 38.4K bps rate, and retaining the default &B1 setting).

2.      The call is under data compression.

3.      You're transmitting text files.  Throughput is higher for text files
    than other types of files, such as .EXE or .COM binary files.

4.      File transfer may be slowed down by a file-transfer protocol.  Many
    non-text files require a file-transfer protocol, but throughput
    results vary.  Certain public domain file-transfer protocols, for
    example, have the following effects.

    Kermit          Newer versions of Kermit support packets up to 9K
            and a sliding window design to eliminate turnaround
            delay.  With earlier versions, however, throughput
            may be severely reduced due to short block lengths
            (possibly under 128 bytes) and acknowledgment
            turnaround time.

    Xmodem          Throughput may be reduced if your version uses short
            block lengths, for example 128 bytes.  Some versions
            use blocks of 1K byte, which is much better, although
            overhead (error control protocol information) still
            affects overall throughput.
    Ymodem          This protocol is similar to Xmodem with 1K byte
            block lengths, and allows multiple files to be sent
            in one transfer.

The above protocols further reduce throughput during error control (ARQ)
connections.  The accuracy of the data is checked twice, by the file-transfer
protocol and the modem.  To avoid redundancy, disable modem error control by
setting the modem to &M0.

The most current version of Zmodem can yield the most efficiency.  Leave the
modem at its error control default (&M4) and data compression default, &K1.
Zmodem performs the same kind of compression as V.42 bis; it turns off its
compression if files are already compressed.

An alternative protocol is Ymodem-G, with the modem left at its error control
default, &M4.  Ymodem-G assumes the modems are handling error control.
Overhead is minimal, with throughput almost equal to that obtained with no
file-transfer protocol.  However, keep in mind that Ymodem-G is only useful
if the modems are using error control.  In addition, follow this
recommendation only if your machine and software support hardware flow
control.

NOTE:  Both modems must use the same protocol for data transfer to take place.

WARNING:  If you are using an X-, Y- or Zmodem-type protocol, do not use the
modem's software flow control.


Achievable Throughput Statistics

The table below indicates the maximum throughput, in characters per second
(cps), that can be expected under the following conditions:

*       Serial port rate set at 57.6K bps; modem set to &B1
    (Your software and computer must support 57.6K bps in order to use
    that rate.)

*       Connection (link) rate of 14.4K bps (assuming no protective fallback
    to a lower speed is necessary)

*       V.42 bis compression negotiated for the call, and the default size
    11-bit, 2048-entry dictionary

*       Straight data (that is, not already compressed, and no file-transfer
    protocol)

*       Transmission from a fast (for example, 386) computer

            Throughput (cps) if set to 14.4K bps

    File Type                       MNP5            V.42 bis

    Assembler or Compiler listing   2880            3840
    Text file                       2325-2625       3400-5760
    Binary file:  .EXE              2175-2400       2030-2600
    Binary file:  .COM              2100-2250       2050-2300
    .ZIP files (common on BBS's)*   1500-1650       1700
    Random binary 8-bit*            1460-1575       1700

* These files are already compressed or appear to the modem to be compressed.
Additional MNP5 compression causes throughput lower than what can be expected
using MNP without compression.  We recommend setting the modem to &K3 when
transferring these files, to allow V.42 bis but disable MNP5.

The following table indicates the maximum throughput, in characters per
second (cps), that can normally be expected in the same conditions as the
previous table, but with a serial port rate of 38.4K bps.

            Throughput (cps) if set to 14.4K bps

    File Type                       MNP5            V.42 bis

Assembler or Compiler listing           2880            3840
Text file                               2325-2625       3400-3840
Binary file:  .EXE                      2175-2400       2030-2600
Binary file:  .COM                      2100-2250       2050-2300
.ZIP files (common on BBS's)*           1500-1650       1700
Random binary 8-bit*                    1460-1575       1700